Kaolinite ( KAY-ə-lə-nete, -lih-; also called kaolin) is a clay mineral, with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6).
Spinel is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl
2O
4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals.
The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula BeAl2O4. The name chrysoberyl is derived from the Greek words χρυσός chrysos and βήρυλλος beryllos, meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and beryl are two completely different gemstones, although they both contain beryllium. Chrysoberyl is the third-hardest frequently encountered natural gemstone and lies at 8.5 on the Mohs scale of mineral hardness, between corundum (9) and topaz (8).
René Just Haüy FRS MWS FRSE was a French priest and mineralogist, commonly styled the Abbé Haüy after he was made an honorary canon of Notre Dame. Due to his innovative work on crystal structure and his four-volume Traité de Minéralogie (1801), he is often referred to as the "Father of Modern Crystallography". During the French Revolution he also helped to establish the metric system.
Ferdinand André Fouqué was a French geologist and petrologist.
Rennes-les-Bains is a commune in the Aude department in southern France.
Willemite is a zinc silicate mineral and a minor ore of zinc. It is highly fluorescent (green) under shortwave ultraviolet light. It occurs in a variety of colors in daylight, in fibrous masses and apple-green gemmy masses. Troostite is a variant in which part of the zinc is partly replaced by manganese, it occurs in solid brown masses.
Alphonse Francois Renard, Belgian geologist and petrographer, was born at Ronse, in East Flanders, on 27 September 1842. He was educated for the church of Rome, and from 1866 to 1869 he was superintendent at the college de la Paix, Namur.
Agardite is a mineral group consisting of agardite-(Y), agardite-(Ce), agardite-(Nd), and agardite-(La). They comprise a group of minerals that are hydrous hydrated arsenates of rare-earth elements (REE) and copper, with the general chemical formula (REE,Ca)Cu6(AsO4)3(OH)6·3H2O. Yttrium, cerium, neodymium, lanthanum, as well as trace to minor amounts of other REEs, are present in their structure. Agardite-(Y) is probably the most often found representative. They form needle-like yellow-green (variably hued) crystals in the hexagonal crystal system. Agardite minerals are a member of the mixite structure group, which has the general chemical formula Cu2+6A(TO4)3(OH)6·3H2O, where A is a REE, Al, Ca, Pb, or Bi, and T is P or As. In addition to the four agardite minerals, the other members of the mixite mineral group are calciopetersite, goudeyite, mixite, petersite-(Ce), petersite-(Y), plumboagardite, and zálesíite.
Mixite is a rare copper bismuth arsenate mineral with formula: BiCu6(AsO4)3(OH)6·3(H2O). It crystallizes in the hexagonal crystal system typically occurring as radiating acicular prisms and massive encrustations. The color varies from white to various shades of green and blue. It has a Mohs hardness of 3.5 to 4 and a specific gravity of 3.8. It has an uneven fracture and a brilliant to adamantine luster.
Georges Friedel was a French mineralogist and crystallographer.
Friedel's law, named after Georges Friedel, is a property of Fourier transforms of real functions.
Friedel's salt is an anion exchanger mineral belonging to the family of the layered double hydroxides (LDHs). It has affinity for anions as chloride and iodide and is capable of retaining them to a certain extent in its crystallographical structure.
Bityite is considered a rare mineral, and it is an endmember to the margarite mica sub-group found within the phyllosilicate group. The mineral was first described by Antoine François Alfred Lacroix in 1908, and later its chemical composition was concluded by Professor Hugo Strunz. Bityite has a close association with beryl, and it generally crystallizes in pseudomorphs after it, or in cavities associated with reformed beryl crystals. The mineral is considered a late-stage constituent in lithium bearing pegmatites, and has only been encountered in a few localities throughout the world. The mineral was named by Lacroix after Mt. Bity, Madagascar from where it was first discovered.
Népouite is a rare nickel silicate mineral which has the apple green color typical of such compounds. It was named by the French mining engineer Edouard Glasser in 1907 after the place where it was first described, the Népoui Mine, Népoui, Poya Commune, North Province, New Caledonia. The ideal formula is Ni3(Si2O5)(OH)4, but most specimens contain some magnesium, and (Ni,Mg)3(Si2O5)(OH)4 is more realistic. There is a similar mineral called lizardite in which all of the nickel is replaced by magnesium, formula Mg3(Si2O5)(OH)4. These two minerals form a series; intermediate compositions are possible, with varying proportions of nickel to magnesium.
Wakefieldite-(Ce) is the cerium analogue of the uncommon rare-earth element vanadate mineral Wakefieldite. It is a member of the xenotime group.
Talmessite is a hydrated calcium magnesium arsenate, often with significant amounts of cobalt or nickel. It was named in 1960 for the type locality, the Talmessi mine, Anarak district, Iran. It forms a series with β-Roselite, where cobalt replaces some of the magnesium, and with gaitite, where zinc replaces the magnesium. All these minerals are members of the fairfieldite group. Talmessite is dimorphic with wendwilsonite.
Maurice Kleman was a French physicist involved in experimental and theoretical studies of the physics of defects; he has covered various fields of research, from condensed matter to heliophysics. As an author, he has been collected by libraries worldwide.
Georges Deicha was a French geologist and mineralogist, known for his pioneering work on fluid inclusions.
Gabriel Delafosse was a French mineralogist who worked at the Natural History Museum in Paris and for sometime at the University of Paris. He contributed to development of the idea of unit cells in crystallography. The mineral Delafossite is named after him. He was one of the founding members of the Société Geologique de France.
